Welding apparatus



Sept. 5,.1944. F, c. HASSE ETAL 2,357,402

WELDING APPARATUS Origihal Fiied March 1. 1940 .A I ll A INVENIII'ORSFRANKLIN C. HASSE ARTHUR BERNARD BY 22% z I ATTQRNEY Patented Sept. 5,1944 WELDING APPARATUS FranklinC. Hasse and Arthur A. Bernard, Chicage,11]., assignors to The Linde Air Products Company, a corporation of OhioOriginal application March- 1, 1940, Serial No.

321,620. Divided and this application November 8, 1941, SerialNo.418,310

6 Claims. (Cl. 113-98) This invention relates to welding apparatus,

and more particularly to apparatus for controlling the temperaturegradient and heat distributionin locally heated metal members.

While the principles of the invention are equally applicable to varioustypes of operations involving the local application of heat to metalmembers, the invention, for the purpose of illustration, will bedescribed in some detail as applied to the weld uniting of metal sheetsand plates of large area such as' those now used extensively in thefabrication of light-weight railway rolling stock.

Welding operations necessitate the local application of a concentratedsource of high temperature heat, the amount of heat applied and thetemperature locally attained depending upon the type of weld' to bemade. Thus, the temperature at the heated area may be only sufllcient torender the meeting surfaces of the members semiplastic, as in forgewelding, or sufilcient to melt is held at temperatures which cause theprecipitation. Under those conditions which produce carbideprecipitation, the steel loses some of its resistance to corrosion, andat the higher temperatures within the range it loses some of itstoughness. The extent of precipitation can be greatly lessened byincreasing the rate at'which the steel passes through the precipitationtemperature range. If austinitic-type stainless steel the meetingsurfaces thoroughly, as in full fusion welding. Although, in weldingoperations the heat is usually applied only to, or adjacent to, thesurfaces to be united, metal adjacent to and remote from the heatedsurfaces is also heatedby conduction from the directly heated surfaces.Such heating, being uneven, tends to warp and distort the weldedarticle.

The problem of shrinking and warping is particularly important in thefabrication of welded structures from large sheets and plates, such asthose which are now used in the construction of railway box cars,gondola-cars, and other rolling stock. As the metal sheets and plates.used in this particular field are relatively thin, theyare peculiarlysusceptible to warping during welding, as the small mass of meta1 is notstrong enough to be resistant to stresses developed by the expension andcontraction incidental to the local-. ized application of heat to themetal plate.

As the grain size is influenced by the time interval during which thetemperature is mainbe rapidly'cooled from above 1800 F. to below 800 F.,its toughness and resistance to corrosion are preserved at their best.

It is among the objects of this invention to provide improved apparatusfor effectively controlling the'heat gradient during'the localizedheating of metal by efliciently conducting heat therefrom at arateproportional to the rate of heat input; to provide an improved apparatusfor preventing the conduction of heat into metal members, which arelocally heated, beyond a point a minimum distance from the point of heatapplication; to provide an improved apparatus for preventing shrinkingand warping 01' metal plates during welding operations, and eliminatingthe n'ecessityfor stress relieving after the welding operation, byreducing the development of internal stresses in such plates during thewelding operation; and to provide an improved apparatus for producingrefined grain structures in welded metals, and for maintaining toughnessand corrosion resistance of austenitic-type stainless -steel duringlocalized heating thereof,

These and other objects of the invention will in part be obvious and inpart become apparent from the following description and the accompanyingdrawing, in which:

Fig. 1 illustrates a typical embodiment of. this invention as it may beused for removing heat during a welding operation; and

Figs. 2 and 3 illustrate modifications of the I embodiment of theinvention shown in Fig. 1.

tained in or above the critical range, it is desirable to cool. themetalrapidly to below the critical range, as soon as possible after ithas been deposited.

Also of importance are the eifects resulting from the localized heatingof such plates when they are made from austinitic-type chromiumnickelstainless steel. When stainless steel of this type is heated between800"F. and 1600 F., inter-granular precipitation of carbides may occur, theextent of the precipitation being afunction of the time interval duringwhich the steel 55 Generally speaking, the invention utilizes thecontrolled application of heat absorbing fluid and/or cooling media,such as liquids or gases, directly in contact with a metal body which isbeing progressively locally heated to an elevated temperature, at a zoneimmediately adjacent to or coextensive with the zone of heatapplication, in' such a manner that a definite heat gradient isestablished from the point of heat application to the point of heatwithdrawal, and the heat absorbing medium isapplied at such rates thatthe rate of heat removal is approximately proportlonal and preferablysubstantially equal tothe rate of heat input. By proper application ofthe heat absorbing medium, with relation to the point of heatapplication, conduction of heat through the remaining mass of metal isrestrained so that the transition zone between the heated the point ofheat application into the main body of the metal of metal, and due tothe small mass which is permitted to attain a high temperature, littleopportunity is afforded for the development of strains and stresses, andconsequently shrinking and warping are minimized and usuallysubstantially eliminated.

The invention is based upon the principle that heat in a body tends tofiow toward the point of lowest temperature. This principle is somewhatanalogous to that of the flow of electric current in a conductor, which,as is common knowledge, fiows in the conductor from a point of highpotential to a point of relatively low potential. Thus, by properlocation of the heat absorbing medium, a heat gradient may beestablished between two points in such zone, which heat gradient issubstantially steeper than any he at gradient between points in suchzone and points in the remaining mass of metal, and the heat may becaused to fiow in a definite path through the heat conductive member. Solong as a point of sufficiently low temperature is maintained at asuitable location adjacent to the point of application of heat, all theapplied heat will tend to flow directly to the point of application ofthe absorbing medium rather than through the adjacent masses of the heatconductive member.

The invention takes cognizance of the fact that water, while a goodabsorber of heat, in that it has a high specific heat, is not a goodconductor thereof. The transfer of heat through water depends largelyupon convection and stirring. The heat from a heated body is absorbed bythe film of water immediately adjacent the heated body but istransmitted only slowly from this film to adjacent films or layers ofwater.

In order to provide effective heat withdrawal it is necessary that thewater be circulated in order that currents may be set up therein and newface of the lower metal member and to cooperate therewith to form asingle fluid-tight channel directly beneath and bridging the line orzone of welding heat application, such fluid-tight channel beingconstructed and arranged for circulating therethrough a heat absorbingmedium under pressure along a portion of said under surface directlyopposite and coextensive with said line. The gasket is carried by arigid support which is constructed and arranged to tightly hold thegasket against said spaced parallel portions of said under surface ofthe lower metal member. The support has a top face which engages andsupports the bottom face of the gasket across its entire width andpresses the parallel marginal portions of the gasket fluid-tightlyagainst the spaced portions of the under surface of the lower metalmember. Thus; a portion of the yieldable gasket provides the entirebottom films of water brought into contact with the heated surface. v

As the heat absorbing medium is circulated in direct contact with theheated members, there is no air film between the. members and themedium. The efliciency of heat absorption is thereby enhanced asubstantial amount, both by the absence of the air film and by thecirculation of the heat absorbing medium. The medium maybe either water,gas, refrigerant, or any other fluid, dependent upon the particular heatrequirements of the particular application. To prevent the heatabsorbing medium remaining in crevices or cracks in the metal, if afluid such as water is used, the circulating system may be dried by asuitable gas or by a vacuum, when the heatingoperation is completed.

Welding apparatus embodying the present invention includes a weldingfixture for use in welding at least one upper metal member to a lowermetal member underlying such member along the line or zone ofapplication of welding heat and extending beyond both sides of said lineor zone. The improved welding fixture comprisesan imperforate,- unitaryor one-piece gasket of yieldable material constructed and arranged toengage-spaced parallel portions of the under-surwall of the fluid-tightchannel and is completely sustained against bulging or failure by therigid support. The improved welding apparatus also includes, incombination with the welding fixture, clamps which are respectivelyconstructed and arranged to engage and bear against the upper surface orsurfaces of the upper metal member or members at points spaced substantially equal distances from the line of welding heat application andoperate to hold the metal members in welding position relatively to saidfixture and the gasket thereof. These clamps are spaced apartsufilciently to leave room between them for applying welding heat to theupper metal member or members along the line or zone of welding heatapplication.

Referring to Fig. 1 of the drawing, a pair of relatively thin sheets orplates P, of considerable area, are illustrated with their adjacentedges in juxtaposition to form a welding seam and iamsition to be weldunited to a similar sheet or plate P by a weld W. The lower metal memberor sheet P underlies the upper metal members or sheets 1? along the lineW of welding heat application and extends laterally on both sides ofsaid line. The sheet P is supported upon a special heat absorbingfixture F, and the sheets P are disposed on sheet P' with their adjacentedges in substantially abutting relation. Clamps C cooperate with thefixture F to hold the work in position for welding. The clamps C.constitute spaced apart abutments bearing against the upper surfaces ofsheets P and positioning the latter relatively to the sheet P. Theclamps Care spaced substantially equal distances from the edges andportions to be weld united, so as ber l2 having a wide, extremelyshallow longitudinal recess I4 formed in its upper surface.

' In cooperation with the spaced clamps C, the

support Ill presses the upper marginal surfaces of the gasket l2 on eachside of the recess ll.

against spaced parallel portions of the under surface of the sheet P, toform with the latter a sirgle fluid-tight channel directly beneath andbridging the line W of welding heat application.

A suitable heat absorbing medium, desirably at 'a sub-atmospherictemperature, is circulated under pressure through longitudinal recess Hto absorb heat from the work at point S. Due to the shape oflongitudinal recess II, the heat absorbing medium is in the form ofathin film, as only the layer of absorbing medium contacting plate Pwill absorb heat, and thus a great depth of heat absorbing medium isunessential and ineflicient; The eifective cooling procedure is tocirculate the medium against plate P under pressure so that a new filmof the medium is constantly coming in contact with the plate.

Under the conditions illustrated,'the portions of the work at the weld Ware at a relativelyhigh temperature, while at pointsA near theextremities of the work, the sheets or plates are at substantiallynormal atmospheric temperature. If no heat absorbing medium were appliedadjacent point S, the heat gradient in the members P, P would extendfrom the weld W to .points A and heat would flow from the weld to pointsA in proportion to the difference between the respective temperatures atthese points. It will be apparent that the work would thus be heated tovarying temperatures throughout substantially all the distance betweenweld W and points A. Consequently, stresses would be set up within theselimits resulting in warping of the sheets upon subsequent coolingthereof.

However, when the proper heat absorbing medium at the propersub-atmospheric temperature is circulated through the narrowlongitudinally extending zone comprising channel ll, the arrangement ofFig. 1 is highly eflicient. As the points is at subatmospherictemperature, the heat passes directly through the work from weld W topoint S where it is absorbed by the heat absorbing medium along a singleline within the heated zone. No heat flows outwardly through the platestoward points A. As an example of l the efliciency of heat absorption,it should be noted that pure India rubber, which softens at about 260F., may be usedfor member l2, although the welding temperatureimmediately adjacent thereto may be in excess of 2700 F., as the heat isall absorbed before it reaches the parts of member. l2 contacting plateP. It should be understood, however, that the member l2 may be formed ofany suitable material such as fibre, copper, or steel, and need notbeformed of rubber.

Fig. 2 illustrates the application of the invention to the weld unitingof at least one upper metal member to a lower metal member under'-'lying the upper member along the line of application of welding heat andextending beyond both sides of said line, and which may form acompletely or partially closed channel or conduit. Thus, in thearrangement of Fig. 2, sheets or plates P are to be weld united to theweb 22 of a U-shaped channel U, against which they are positioned byclamps C. The open side of the channel is closed by a bracket 2",supporting a suitable gasket 26 engaging the channel flanges 28. thesupport 24 presses the. upper marginal surfaces of the gasket 26 againstthe under surface In cooperation with the spaced clampsCg as a pair ofsheets or structural members P,

.which are to be weld united to a lower metal member comprising angle Eby a weld W extending along the corner of the angle E, are arrangedin'overlapping relation with the outer surface of the legs of the angleand with their edges in adjacent relation. The angle E underlies theupper metal member along the line W of application of welding heat andextends on both sides of said line. A special fixture F is used as partof the cooling medium conduit and work supporting means and, duringwelding, cooperates with the spaced clamps C to hold the metal membersin welding position, the room between the clamps being sufficient forapplying the welding heat to and along the corner of the. assembly toproduce the weld W. This fixture comprises a bracket 34 and a' gasket 36having perpendicularly related opposed longitudinal bevelled edges 38which are pressed by the support 34 in fluidtight engagement with theunder surfaces respectively of the legs of the angle E, constitutinspaced parallel portions of the lower of the members to be weld united,thereby forming, in conjunction with the interior surface of angle E, asinglefluid-tight triangular channel or conduit 40 for the heatabsorbing medium. The medium circulated under pressure through channel40 directly beneath and bridging the line of welding heat application,absorbs heat at point S,'establishing thereby a single steep heatgradient through weld W. No heat flows through the members P or E to thepoints A.

From the foregoing description, it will be apparent that the inventionis based upon the laws of heat flow. By establishing a point atrelatively low temperature immediately adjacent the welding zone, asteep heat, gradient is provided causing applied heat units to flow tothis point and preventing flow of heat outwardly through the metallicmembers. heat absorbing properties of water or other heat absorbingmedia are used effectively, while the low heat conductivity of suchmedia is overcome by using shallow films or strata of the media cir--culating under pressure in contact with the work at the welding point.Warping is prevented as there is'substantially no heating of metalbeyond a point a few thousandths of an inch from the welding zone, anddue to the rapid absorption of heat by the heat absorbing media.

As distinguished from prior apparatus, in which a heat absorbing mediumhas been applied to the work at points spaced a substantial distancefrom the zone of heat application, the

, present invention resides in the application of steep heat gradientthrough the heated zone,

of the spaced parallel channel flanges 26, to form with the latter asingle fluid-tight channel directly beneath and bridging the line W ofwelding' heat application. Heat flows through weld W to point S where itis absorbed rapidly by a heat absorbingmedium circulated under pressurethrough the conduit'formed .by channel U and gasket 26. No heat flowsthrough the sheets to points'A'in the arrangement of Fig. 2.

Fig. 3 illustrates the application of the invention to the formation ofangular or corner welds. In Fig. 3, at least one upper metal member,such and no heat flows outwardly therefrom through the work. On-theother hand, in such prior apparatus, heat gradients are establishedthrough substantial portions of the work, resulting in warping thereof.

Additionally, when the invention is applied to the welding of. stainlesssteel,'loss of the protecting chromium from the grains is prevented dueto the extremely rapid rate at which heat is withdrawn from the metaland due to the very narrow heat afiected zone.

While certain embodiments of the invention Furthermore, the high havebeen illustrated and described in order to furnish a clear understandingof the principles involved, it will be obvious to those skilled in theart that the invention may be otherwise embodied and practiced withoutdeparting from the principles or exceeding the scope of the invention.

This application is a division of our copending application Serial No.321,620, filed March 1,

1940, now Patent No. 2,280,150, issued April 21,

What is claimed is:

1. Welding apparatus for use inwelding at least one upper metal memberto a lower metal member underlying such upper member along the line ofapplication of welding heat and extending beyond both sides of-saidline,'said apparatus comprising, unitary gasket of yieldable materialconstructed and arranged to engage spaced parallel portions of the undersurface of such lower member and to cooperate therewith to form a singlefluidtight channel directly beneath and bridging such line of weldingheat application, a portion of said gasket providing the entire bottomwall of said channel, said fluid-tight channel being constructed andarranged for circulating therethrough a heat absorbing medium underpresmetal member along such line of welding. heat application.

2. Welding apparatus as claimed in claim 1, wherein said imperforateunitary gasket consists entirely of rubber which softens at about 260 F.

in combination, an imperforate- 3. Welding apparatus as claimed in claim1,

wherein said imperforate unitary gasket has a shallow longitudinallyextending recess in its upper surface and upper marginal portionsadjoining and coextensive with said recess, such marginal portionsbeing'constructed and arranged to engage the under surface ofsuch lowermember and to cooperate with the latter and said recess to form suchsingle fluid-tight channel directly beneath and bridging the line ofwelding heat application, said support being constructed and arranged tocooperate with said clamps and hold said marginal portions of saidgasket fluid-tightly against said under surface.

4. Welding apparatus for use in welding at least one upper metal memberto the web of a lower metal channel member underlying and contactingsuch upper member along the line of application of welding heat andhaving depending flanges spaced from both sides of said line, saidapparatus comprising, in combination, an imperforate unitary gasket ofyieldable material adapted to engage the flanges of such lower channelmember and to cooperate with such arranged for circulatingtherethrough aheat absorbing medium under pressure along a portion of the undersurface of said channel web directly opposite and coextensive with saidline; a support for said gasket constructed and arranged to tightly holdmarginal portions of said gasket against the flanges of said channelmemher; and clamps spaced apart and respectively constructed .andarranged to engage the upper surface of such upper metal member atpointsspaced substantially equal distances from said line, to hold such metalmembers in welding position relatively to said gasket and said supportand to leave room betweensaid clamps for applying welding heat to saidupper metal member along said line.

5. Welding apparatus for use in welding at least one upper metal memberto a lower metal angle member underlying such upper member along theline of application of welding heat and having legs respectivelyextending laterally beyond both sides of said line, said apparatuscomprising, in combination, an imperforate unitary gasket of yieldablematerial having bevelled marginal surfaces respectively constructed andarranged to engage the under surface of each leg of such angle memberand to cooperate with such legs to form a single .iiuidtight channel oftriangular cross-section directly adjoining and bridging such line ofwelding heat application, a portion of said gasket providing the entirebottom" wall of said charmel, said fluid-tight channel being constructedand arranged for circulating therethrough a heat absorbing medium underpressure along a portion of the interior surface of said angle memberdirectly opposite and coextensive with said line;

a support for said imperforate unitary gasket constructed and arrangedto hold the bevelled marginal surface of said gasket fluid-tightlyagainst the legs of said angle member; and clamps spaced apart andrespectively constructed and arranged to engage the upper surface ofsuch upper metal member at points laterally spaced from said line ofwelding heat application, to hold such members in welding positionrelatively to said gasket and said support and to leav room between saidclamps for applying welding heat to said upper member along said line. a

6. Weldin apparatus for use in welding at least one upper metal memberto a lower metal member underlying such upper member along the line ofapplication of welding heat and adjacent both sides of said line, saidapparatus comprising, in combination, an imperforate unitary gasketconsisting entirely of yieldable material and having marginal portionsconstructed and arranged to engage spaced parallel portions of the undersurface of such lower member and to cooperate with the latter to form asingle fluid-tight channel directly beneath andbridging such line ofwelding heat application, said fluid-tight channel being constructed andarranged for circulating therethrough a heat absorbing medium underpressure along a portion of said under surface flanges to form a singlefluid-tight conduit I directly beneath and bridging such line ofwelddirectly opposite said line; a rigid support for said yieldablegasket constructed and arranged to engage and support the bottom face ofsaid gasket and to press said marginal portions fluidtightly againstsaid spaced portions of said under surface, that portion of saidyieldable gasket disposed between said marginal portions constitutingthe entire bottom wall of said fluidposition relatlvely'to said gasketand said support and to leave room between said clamps for applyingwelding heat directly to such upper metal member along said line. .a

FRANKLIN c. HASSE. ARTHUR A. BERNARD.

